The incorporation of PCM materials such as fatty acids, salts or paraffins in particular into polymeric matrices for releasing or absorbing heat via a change of state owing to the latent heat of fusion which characterizes these PCMs has been known for a long time. Indeed, these PCMs have the advantage of changing from the liquid state to the solid state while releasing heat during the crystallization thereof, and conversely of changing from the solid state to the liquid state while absorbing heat during the melting thereof. It is known, nonlimitingly, to use these PCMs in powder form with nodules dispersed in a thermoplastic or elastomer matrix, or by encapsulating them in microspheres, for example plastic microspheres, or else by grafting them to a support.
Document U.S. Pat. No. 7,488,773 presents crosslinked rubber compositions for example for buildings, motor vehicles or the thermal protection of products, which were prepared from a two-component RTV silicone elastomer with the name ELASTOSIL® RT 621 in which a PCM was dispersed. More specifically, this PCM is of non-encapsulated type and, in the examples for the preparation of these compositions, it consists of n-hexadecane, eicosane or a lithium salt which all have melting points below 40° C., it being specified that this PCM is melted in order to mix it in the liquid state with that of the components of the silicone elastomer which comprises the crosslinking agent. As regards the weight fraction of PCM in these compositions thus prepared, it is 30%, which is equivalent to an amount of PCM of around only 43 phr (phr: parts by weight per hundred parts of silicone elastomer).
One major drawback of the compositions prepared in that document lies in the reduced amount of PCM—much less than 100 phr—that it is possible to disperse in this silicone elastomer, which is detrimental in particular to the change of state enthalpy per unit mass ΔH obtained for these compositions (which is between 50 J/g and 70 J/g only in the examples from that document) and therefore the ability of these compositions to absorb and release the thermal energy required by certain applications and environments that are particularly demanding as regards warming a space or fluid, for example.